I've equipped 2 melee weapons in the Xbox versions of D2:ED and DKS. In D2:ED there were separate listings in the equipment menu for the main hand and off-hand, so duel wielding was pretty straightforward.
In DKS, equipping weapons puts them in the main hand by default (the hand icon on the left of the character model in the inventory window). If you select the hand icon on the right of the character and hit A, you should be able to select a one handed weapon to equip in your off-hand.
